Packaging structure based on pre-packaging technology, packaging method and application thereof

Abstract

The invention discloses a packaging structure based on a pre-packaging technology, a packaging method and application of the packaging structure, the packaging structure comprises plastic packaging units and a pre-plastic packaging body, the plastic packaging units are distributed on a substrate in an array mode, each plastic packaging unit comprises a base island, an inner pin bonding pad, an outer pin bonding pad and a heat dissipation area, the pre-plastic packaging body is packaged to the substrate through a plastic packaging mold, and the inner pin bonding pad and the outer pin bonding pad are arranged on the base island. A plastic package area is arranged in the middle of the pre-plastic package body, and the plastic package unit is arranged in the plastic package area in a plastic package mode. According to the invention, the pre-packaging technology and the plastic packaging technology are adopted, the plastic packaging material is plastically packaged on the substrate through the plastic packaging mold, and through the pre-plastic packaging technology, the strength of the packaging body is greatly improved, the cost of the packaging process is reduced, and the packaging reliability is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor packaging technology, and in particular to a packaging structure based on pre-packaging technology, a packaging method and applications thereof. Background Art

[0002] With the vigorous rise of a new round of technological revolution and industrial transformation such as 5G, big data, and artificial intelligence, display applications are constantly upgrading. As an important port for intelligent interaction, new displays have become an important support and foundation for emerging industries such as ultra-high-definition video, the Internet of Things, and virtual reality. Micro LED display has excellent characteristics such as high luminous efficiency, high brightness, short response time, and good reliability, and has become one of the focuses of science and technology in recent years.

[0003] In order to improve the heat dissipation performance and reliability of existing Micro LED chips in the package, the existing technology mostly adopts COB (Chips on Board) chip packaging technology. This technology is to prevent the bare chip from being directly exposed to the air, contaminated or damaged by human factors, affecting or destroying the chip function, and mostly uses packaging glue to directly cover the chip and the bonding wire. Its disadvantages are that the packaging cost is too high, the packaging yield is low, and the color uniformity is poor. Summary of the invention

[0004] The present invention provides a packaging structure, packaging method and application based on pre-packaging technology, aiming to solve the problems of high packaging cost, low packaging body strength and low packaging body reliability in the prior art. The present invention uses pre-packaging technology to plasticize the epoxy resin plastic packaging body around the product, thereby improving the product strength and reliability, and uses phosphor glue spray molding technology to cover the phosphor glue on the chip surface, thereby greatly improving the color uniformity of the product.

[0005] The technical solution provided by the present invention is as follows:

[0006] A first aspect of the present invention provides a packaging structure based on pre-packaging technology, comprising a plastic packaging unit and a pre-plastic packaging body;

[0007] The plastic encapsulation unit array is distributed on the substrate, the front of the plastic encapsulation unit is provided with a base island and an inner pin pad, the base island is electrically connected to the inner pin pad, the back of the plastic encapsulation unit is provided with an outer pin pad and a heat dissipation area, and the base island is provided with an upper core area;

[0008] The pre-molded body is molded onto the substrate by a molding mold adapted to the molding unit. A molding area is provided in the middle of the pre-molded body. The molding unit is molded in the molding area, and the external pin pads and heat dissipation area of ​​the molding unit are exposed from the pre-molded body.

[0009] Furthermore, it also includes a chip, which is arranged in the upper core area of ​​the base island, and the chip is electrically connected to the base island through bonding wires.

[0010] Furthermore, a phosphor glue layer is coated on the chip, a first glue layer is coated around the chip, a second glue layer is coated between the chip and the pre-plastic package, and the height of the second glue layer is lower than that of the first glue layer.

[0011] Furthermore, the first adhesive layer is made of highly thixotropic white glue;

[0012] The second adhesive layer is made of high-fluidity white adhesive.

[0013] Furthermore, the chip is a Micro LED chip, and the Micro LED chip is bonded with a Micro LED matrix through a bonding process;

[0014] The substrate is made of BT material;

[0015] The pre-plastic encapsulation body is made of epoxy resin;

[0016] The bonding wire is made of copper wire, aluminum wire, palladium-plated copper wire, gold wire, silver wire or silver alloy wire.

[0017] A second aspect of the present invention provides a packaging method based on pre-packaging technology, which is used to package the above-mentioned packaging structure based on pre-packaging technology, comprising the following steps:

[0018] A substrate, a chip and a plastic encapsulation mold are provided, wherein the plastic encapsulation units are distributed in an array on the substrate, the plastic encapsulation mold matches the plastic encapsulation units, and a Micro LED matrix is ​​bonded to the chip through a bonding process;

[0019] The molding compound is molded by the molding mold to form a pre-molded body, and the molding unit is molded in the pre-molded body by hot pressing;

[0020] Performing core loading, placing the chip on the core loading area on the base island, and electrically connecting the chip to the substrate through bonding wires;

[0021] Evenly mix transparent silica gel, phosphor and diluent, defoam after mixing to obtain phosphor glue, and evenly spray the phosphor glue on the surface of Micro LED matrix;

[0022] Use a dispensing device to apply the first white glue to the outside and surrounding of the Micro LED matrix surface to form a dam;

[0023] Use a dispensing device to apply a second white glue between the dam and the pre-plastic encapsulation body to form a second glue layer, so that the second white glue wraps the bonding wire and the pin pad portion inside the substrate, and the height of the second white glue is lower than the height of the dam, and the plastic encapsulation is completed after the second white glue is cured;

[0024] After the plastic packaging is completed, the plastic packaging product is cut.

[0025] Further, the molding material is molded onto the substrate through the molding mold to form a pre-molded body, and the molding unit is molded in the pre-molded body through hot pressing, specifically:

[0026] The epoxy resin molding material is molded onto the substrate through a bowl-cup-shaped molding mold by a molding process to form a bowl-cup-shaped pre-molded body. The pre-molded body is tightly combined by a hot pressing process and post-cured at high temperature so that the molding unit is molded inside the pre-molded body.

[0027] Further, the chip placement is performed by placing the chip on the chip placement area on the base island and electrically connecting the chip to the substrate through bonding wires, including:

[0028] Use a die bonding machine to apply silver glue to the upper core area of ​​the base island, and use an upper core suction nozzle to place the chip on the silver glue. During the placement process, the die bonding accuracy is controlled to ensure that the Micro LED matrix on the surface of the chip is not crushed, and the chip position is controlled within ±20um and the angle is controlled within ±5°. After placement, the silver glue is cured in an oven to generate a cross-linking reaction between the silver glue and the chip and the base island, so that the chip is tightly connected to the base island;

[0029] The bonding wire is used to tightly weld the inner pin pad to achieve electrical connection between the chip and the substrate.

[0030] Furthermore, the transparent silica gel, the phosphor and the diluent are uniformly mixed, and after the mixing, the phosphor glue is defoamed to obtain the phosphor glue, and the phosphor glue is uniformly sprayed on the surface of the Micro LED matrix, specifically:

[0031] The transparent silica gel, phosphor and diluent are uniformly mixed by using a glue mixing device, and after mixing, the internal bubbles are eliminated by using a defoaming device to obtain phosphor glue, and the phosphor glue is uniformly sprayed on the surface of the Micro LED matrix by using a glue spraying device.

[0032] A third aspect of the present invention provides a packaging product, which adopts the above-mentioned packaging structure based on pre-packaging technology, or is prepared using the above-mentioned packaging method based on pre-packaging technology, and the packaging product is used for Micro LED smart car lights.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention adopts pre-packaging technology and utilizes the plastic packaging process to plasticize the epoxy resin plastic packaging material onto the substrate through a bowl-shaped plastic packaging mold. The pre-plastic packaging process greatly improves the strength of the package body, reduces the cost of the packaging process, and improves the reliability of the package. The present invention divides the glue dispensing steps into three steps: dispensing phosphor glue, dam, and dispensing white glue, which improves the glue dispensing accuracy and solves the problem that the glue dispensing flatness of large-volume Micro LED chips is difficult to control. The shape accuracy of the package body is improved, so that the product obtains a more accurate and excellent optical effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of a substrate in an embodiment of the present invention;

[0036] Figure 2 This is a structural diagram of a pre-package in an embodiment of the present invention;

[0037] Figure 3 It is an assembly diagram of a substrate and a pre-packaged body in an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the front structure of the plastic-sealed product in an embodiment of the present invention;

[0039] Figure 5 It is a schematic diagram of the back structure of the plastic-sealed product in an embodiment of the present invention.

[0040] The reference numerals are as follows:

[0041] 1-substrate, 2-plastic encapsulation unit, 3-base island, 4-pre-plastic encapsulation body, 5-plastic encapsulation area, 6-chip, 7-phosphor glue layer, 8-second glue layer, 9-external pin pad, 10-packaging structure, 11-heat dissipation area. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the embodiments described below are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0043] Therefore, the detailed description of the embodiments of the present application provided below in conjunction with the accompanying drawings is intended to represent only selected embodiments of the present application, and is not intended to limit the scope of protection claimed in the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0044] It should be understood that in the description of the embodiments of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0045] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0046] See also Figure 1-Figure 3 The present invention provides a packaging structure 10 based on pre-packaging technology, including a plastic packaging unit 2 and a pre-plastic packaging body 4.

[0047] The plastic encapsulation unit 2 is arranged in an array on the substrate 1. The front side of the plastic encapsulation unit 2 is provided with a base island 3 and an inner pin pad, the base island 3 is electrically connected to the inner pin pad, and the back side of the plastic encapsulation unit 2 is provided with an outer pin pad 9 and a heat dissipation area 11 (such as Figure 5 As shown in FIG. 1 , a core region is disposed on the base island 3. The structure of the substrate 1 and the plastic encapsulation unit 2 is as shown in FIG. Figure 1 As shown, the structure of the pre-molded body 4 is as follows Figure 2 shown.

[0048] The pre-molded body 4 is molded onto the substrate 1 by a molding mold adapted to the molding unit 2. A molding area 5 is provided in the middle of the pre-molded body 4. Figure 2 As shown, the plastic encapsulation unit 2 is plastic encapsulated in the plastic encapsulation area 5, and the external pin pads 9 and the heat dissipation area 11 of the plastic encapsulation unit 2 are exposed from the pre-plastic encapsulation body 4, thereby improving the heat dissipation effect.

[0049] Figure 3 It is a schematic diagram of a packaging structure 10 formed by the plastic packaging unit 2 being plastic-sealed in the pre-plastic packaging body 4, and the packaging structure is not equipped with a control chip.

[0050] Optionally, the packaging structure also includes a chip 6, which is arranged in the upper core area of ​​the base island 3, and the chip 6 is electrically connected to the base island 3 through bonding wires. Specifically, the chip 6 is connected to the inner pin pad and / or the outer pin pad 9 on the base island 3 through bonding wires.

[0051] Optionally, a phosphor glue layer 7 is coated on the chip 6, a first glue layer is coated around the chip 6, a second glue layer 8 is coated between the chip 6 and the pre-molded body 4, and the height of the second glue layer 8 is lower than the first glue layer. The phosphor glue layer 7 enables the product to obtain a more accurate and excellent optical effect, and the first glue layer and the second glue layer 8 are used to physically protect the chip and isolate it from external water vapor, thereby increasing its reliability.

[0052] Figure 4 This is the front view of the package product structure after chip 6 is installed. Figure 5 This is the back view of the packaged product.

[0053] Optionally, the first adhesive layer is made of highly thixotropic white glue, such as Kraft K-5928 organic silicone rubber.

[0054] The second adhesive layer 8 is made of high-fluidity white glue, such as Japanese ThreeBond TB-1211 white glue.

[0055] Optionally, chip 6 is a Micro LED chip, and the Micro LED chip is bonded with a Micro LED matrix through a bonding process, so that the product has the required light type, good optical effect, and more precise control.

[0056] The substrate 1 is made of BT material.

[0057] The pre-molded body 4 is made of epoxy resin.

[0058] The bonding wire is made of copper wire, aluminum wire, palladium-plated copper wire, gold wire, silver wire or silver alloy wire.

[0059] The present invention also provides a packaging method based on pre-packaging technology, which is used to package the above-mentioned packaging structure based on pre-packaging technology, comprising the following steps:

[0060] Step 101, providing a substrate 1, a chip 6 and a plastic encapsulation mold, wherein the plastic encapsulation units 2 are distributed in an array on the substrate 1, the plastic encapsulation mold matches the plastic encapsulation units 2, and a Micro LED matrix is ​​bonded to the chip 3 through a bonding process.

[0061] In step 101, the plastic encapsulation mold is matched with the plastic encapsulation unit 2 to be encapsulated, so that the plastic encapsulation unit 2 can be well encapsulated in the pre-encapsulated body 4 prepared by the plastic encapsulation mold. In this embodiment, a MicroLED smart car light package is realized by this method. The substrate 1 and the chip 6 are related to the MicroLED smart car light. The structure of the substrate 1 and the plastic encapsulation unit 2 thereon is as follows: Figure 1 As shown, based on the structure of the plastic encapsulation unit 2, a plastic encapsulation mold with a bowl-cup structure is designed, and the structure of the pre-plastic encapsulation body 4 prepared by the plastic encapsulation mold is as shown in FIG. Figure 2As shown. The substrate 1 without pre-molding includes a middle BT resin layer, a copper foil layer, and a solder mask layer. A hole is punched in the middle of the BT layer to achieve thermal conduction and electrical connection of the copper foil layers on the front and back sides of the substrate 1. The front copper foil layer includes the middle base island 3 and the inner pin pads and circuit parts around the base island 3. The back copper foil layer includes the outer pin pads 9 and the heat dissipation area 11.

[0062] Step 102: Plastic sealing of substrate

[0063] The molding compound is formed into a pre-molded body 4 through a molding mold, and the molding unit 2 is molded in the pre-molded body 4 through heat pressing.

[0064] The method provided by the present invention is different from the traditional packaging method, the main difference being that the method first prepares a pre-molded body 4 through a plastic packaging mold, and then places the plastic packaging unit 2 in the pre-molded body 4 for plastic packaging. The pre-molded packaging process greatly improves the strength of the package, reduces the cost of the packaging process, and improves the packaging reliability.

[0065] Step 103: Perform core placement and wire bonding

[0066] The chip 6 is placed on the upper core region of the base island 3 , and the chip 6 is electrically connected to the substrate 1 through bonding wires.

[0067] Step 104: Glue application (fluorescent glue)

[0068] The transparent silica gel, phosphor and diluent are uniformly mixed, and after mixing, the phosphor glue is defoamed to obtain phosphor glue, and the phosphor glue is uniformly sprayed on the surface of the Micro LED matrix to form a phosphor glue layer 7.

[0069] Step 105: First white glue dispensing (dam)

[0070] The first white glue is applied to the outside and surrounding of the surface of the Micro LED matrix by using a dispensing device to form a dam (i.e., the first glue layer). The first white glue is a highly thixotropic white glue. In this embodiment, Kraft K-5928 organic silicone rubber can be used.

[0071] Step 106: Second white glue dispensing

[0072] The second white glue is applied between the dam and the pre-molded body by using a dispensing device to form a second glue layer 8, so that the second white glue wraps the bonding wire and the pin pad portion inside the substrate. The height of the second glue layer 8 is lower than the height of the dam, and the plastic sealing is completed after the second white glue is cured. The second white glue is a high-flow white glue, and in this embodiment, Japanese ThreeBond TB-1211 white glue can be used.

[0073] Step 107: Cutting

[0074] After the plastic sealing is completed, the plastic sealed product is cut. Specifically, the product that has completed the above steps is placed on the blue film and fixed, and is cut using a high-speed cutting knife.

[0075] Optionally, in step 102, the molding material is molded onto the substrate through a molding mold to form a pre-molded body, and the molding unit is molded in the pre-molded body through hot pressing, specifically:

[0076] The epoxy resin molding material is molded onto the substrate 1 through a bowl-shaped molding mold using a molding process to form a bowl-shaped pre-molded body 4. The pre-molded body 4 is tightly combined through a hot pressing process and post-cured at high temperature, so that the molding unit 2 is molded in the pre-molded body 4.

[0077] Optionally, in step 103, placing the chip on the upper core region of the base island and electrically connecting the chip to the substrate through bonding wires includes:

[0078] Step 1031, use a die bonding machine to apply silver glue to the upper core area of ​​the base island 3, and use an upper core suction nozzle to place the chip 6 on the silver glue. The placement process controls the die bonding accuracy to ensure that the Micro LED matrix on the surface of the chip 6 is not crushed, and ensure that the position of the chip 6 is controlled within ±20um and the angle is controlled within ±5° with respect to the designed position. After placement, the silver glue is cured in an oven to produce a cross-linking reaction between the silver glue and the chip 6 and the base island 3, so that the chip 6 and the base island 3 are tightly connected.

[0079] Step 1032 , use bonding wire to tightly weld the inner pin pad to achieve electrical connection between the chip 6 and the substrate 1 .

[0080] Optionally, transparent silica gel, phosphor and diluent are uniformly mixed, and after mixing, the phosphor glue is defoamed to obtain phosphor glue, and the phosphor glue is uniformly sprayed on the surface of the Micro LED matrix, specifically:

[0081] Use glue mixing equipment to evenly mix transparent silica gel, phosphor and diluent. After mixing, use defoaming equipment to eliminate internal bubbles to obtain phosphor glue. Use glue spraying equipment to evenly spray the phosphor glue on the surface of the Micro LED matrix.

[0082] The present invention adopts pre-packaging technology and utilizes the plastic packaging process to plasticize the epoxy resin plastic packaging material onto the substrate through a bowl-shaped plastic packaging mold. The pre-plastic packaging process greatly improves the strength of the package body, reduces the cost of the packaging process, and improves the reliability of the package. The present invention divides the glue dispensing steps into three steps: dispensing phosphor glue, dam, and dispensing white glue, which improves the glue dispensing accuracy and solves the problem that the glue dispensing flatness of large-volume Micro LED chips is difficult to control. The shape accuracy of the package body is improved, so that the product obtains a more accurate and excellent optical effect.

[0083] The above is only the best specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application shall be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A packaging structure based on pre-packaging technology, characterized in that: It includes a plastic sealing unit and a pre-plastic sealing body; The plastic encapsulation unit array is distributed on the substrate, the front of the plastic encapsulation unit is provided with a base island and an inner pin pad, the base island is electrically connected to the inner pin pad, the back of the plastic encapsulation unit is provided with an outer pin pad and a heat dissipation area, and the base island is provided with an upper core area; The pre-molded body is molded onto the substrate by a molding mold adapted to the molding unit. A molding area is provided in the middle of the pre-molded body. The molding unit is molded in the molding area, and the external pin pads and heat dissipation area of ​​the molding unit are exposed from the pre-molded body.

2. The packaging structure based on pre-packaging technology according to claim 1, characterized in that: It also includes a chip, which is arranged in the upper core area of ​​the base island, and the chip is electrically connected to the base island through bonding wires.

3. The packaging structure based on pre-packaging technology according to claim 2, characterized in that: The chip is coated with a layer of phosphor glue, the chip is coated with a first glue layer around it, and a second glue layer is coated between the chip and the pre-plastic package, and the height of the second glue layer is lower than that of the first glue layer.

4. The packaging structure based on pre-packaging technology according to claim 3, characterized in that: The material of the first adhesive layer is highly thixotropic white adhesive; The second adhesive layer is made of high-fluidity white adhesive.

5. The packaging structure based on pre-packaging technology according to any one of claims 2 to 4, characterized in that: The chip is a Micro LED chip, and the Micro LED chip is bonded to a Micro LED matrix through a bonding process; The substrate is made of BT material; The pre-plastic encapsulation body is made of epoxy resin; The bonding wire is made of copper wire, aluminum wire, palladium-plated copper wire, gold wire, silver wire or silver alloy wire.

6. A packaging method based on pre-packaging technology, used for packaging the packaging structure based on pre-packaging technology as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: A substrate, a chip and a plastic encapsulation mold are provided, wherein the plastic encapsulation units are distributed in an array on the substrate, the plastic encapsulation mold matches the plastic encapsulation units, and a Micro LED matrix is ​​bonded to the chip through a bonding process; The molding compound is molded by the molding mold to form a pre-molded body, and the molding unit is molded in the pre-molded body by hot pressing; Performing core loading, placing the chip on the core loading area on the base island, and electrically connecting the chip to the substrate through bonding wires; Evenly mix transparent silica gel, phosphor and diluent, defoam after mixing to obtain phosphor glue, and evenly spray the phosphor glue on the surface of Micro LED matrix; Using a dispensing device to apply the first white glue to the outside and surrounding of the Micro LED matrix surface to form a dam; Use a dispensing device to apply a second white glue between the dam and the pre-plastic encapsulation body, so that the second white glue wraps the bonding wire and the pin pad portion inside the substrate, and the height of the second white glue is lower than the height of the dam, and the plastic encapsulation is completed after the second white glue is cured; After the plastic packaging is completed, the plastic packaging product is cut.

7. The packaging method based on pre-packaging technology according to claim 6, characterized in that: The molding compound is passed through the molding mold to form a pre-molded body, and the molding unit is molded in the pre-molded body by hot pressing, specifically: The epoxy resin molding material is molded onto the substrate through a bowl-cup-shaped molding mold by a molding process to form a bowl-cup-shaped pre-molded body. The pre-molded body is tightly combined by a hot pressing process and post-cured at high temperature so that the molding unit is molded inside the pre-molded body.

8. The packaging method based on pre-packaging technology according to claim 6, characterized in that: The chip placement is performed by placing the chip on the chip placement area on the base island, and electrically connecting the chip to the substrate through bonding wires, including: Use a die bonding machine to apply silver glue to the upper core area of ​​the base island, and use an upper core suction nozzle to place the chip on the silver glue. During the placement process, the die bonding accuracy is controlled to ensure that the Micro LED matrix on the surface of the chip is not crushed, and the chip position is controlled within ±20um and the angle is controlled within ±5°. After placement, the silver glue is cured in an oven to generate a cross-linking reaction between the silver glue and the chip and the base island, so that the chip is tightly connected to the base island; The bonding wire is used to tightly weld the inner pin pad to achieve electrical connection between the chip and the substrate.

9. The packaging method based on pre-packaging technology according to claim 6, characterized in that: The transparent silica gel, phosphor and diluent are uniformly mixed, and after mixing, the phosphor glue is defoamed to obtain the phosphor glue, and the phosphor glue is uniformly sprayed on the surface of the MicroLED matrix, specifically: The transparent silica gel, phosphor and diluent are uniformly mixed by using a glue mixing device, and after mixing, the internal bubbles are eliminated by using a defoaming device to obtain phosphor glue, and the phosphor glue is uniformly sprayed on the surface of the Micro LED matrix by using a glue spraying device.

10. A packaged product, prepared by using the package structure based on pre-package technology as claimed in any one of claims 1 to 5, or by using the package method based on pre-package technology as claimed in any one of claims 6 to 9, characterized in that: The packaging product is used for Micro LED smart car lights.

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